Certain 5-acyl-2-benzimidazolylcarbamates have anthelmintic activity, U.S. Pat. No. 3,657,267. Mebendazole, a marketed member of this group, is methyl (5-benzoyl-1H-benzimidazol-2-yl)carbamate. Of course, such compounds do not have the 1-phenylethenyl substituent which distinguishes the structures of the compounds of this invention.